I also remember Sweden being like this until early/mid 90s. The only real change AFAIK was peoples' attitudes, as a result of government campaigns.

Hell, in the 60s you could watch wonderfully informational movies as this on the one and only available TV station https://www.youtube.com/watch?v=XrcrX9Qaw2o. (skip to 1:15 for the recommended practise of waste removal near the ocean).